Module containing some specialized functions to deal with tags.
This Module follows certain conventions. My advice is to stick with them if
possible.

More concrete: all functions in this module assume that the tags are
located in the tags field, and separated by commas. An example file
foo.markdown could look like:

---
author: Philip K. Dick
title: Do androids dream of electric sheep?
tags: future, science fiction, humanoid
---
The novel is set in a post-apocalyptic near future, where the Earth and
its populations have been damaged greatly by Nuclear...

All the following functions would work with such a format. In addition to
tags, Hakyll also supports categories. The convention when using categories
is to place pages in subdirectories.

An example, the page posts/coding/2010-01-28-hakyll-categories.markdown
Tags or categories are read using the readTags and readCategory
functions. This module only provides functions to work with tags:
categories are represented as tags. This is perfectly possible: categories
only have an additional restriction that a page can only have one category
(instead of multiple tags).